A {Trash} effect can be triggered/activated while its card is in the trash. Such effects can't be triggered or activated in areas other than the trash.

The effects trigger simultaneously, so the player can choose the activation order. However, if you use this card's {Trash} [Your Turn] effect to digivolve that Digimon before activating EX10-009 [Creepymon]'s [When Attacking] effect, you won't be able to activate that [When Attacking] effect.

Yes, it's met.

No, you can't. You can only activate this card's {Trash} [Your Turn] effect if it's already in the trash upon the timing when you make the attack declaration for your [Creepymon]. If this card is placed in the trash by an effect that activates after making the attack declaration for your [Creepymon], this card's {Trash} [Your Turn] effect won't trigger and you can't activate it.